In general, many components mounted on an electronic device are joined by soldering such as surface mounting. However, a soldered portion such as a solder bump applied to surface mounting is gradually deteriorated by thermal fatigue arising from operation of the electronic device, and a crack or the like extends and a fracture occurs depending on the circumstances, to sometimes cause continuity failure.
So, in order for prior evaluation of a deterioration condition (extension of a crack or the like) of a soldered portion or in order to analyze a mechanism of defect occurrence in the soldered portion, a defect inspection method enabling a nondestructive inspection is utilized. In the inspection method of such a kind, inspection is carried out by visualizing a defect such as a crack occurring in a soldered portion by means of a see-through image generated by an X-ray observation apparatus or an X-ray CT (Computed Tomography) apparatus.
However, in the aforementioned defect inspection method, since an X-ray absorptance (X-ray attenuation factor) of solder is high, the soldered portion comes out dark overall on the see-through image by the X-ray. Thus, it is difficult to detect a comparatively small crack or the like occurring in the soldered portion. Note that, other than the above, there is a request for enabling accurate detection of a defect occurring in a resin molded article or a metal component other than solder.